JPH055067B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention provides a system in which a three-phase interrupting section is used when switching a substation busbar or power transmission line by switching equipment housed in the same grounded metal container. The present invention relates to a device used in a disconnection test method for verifying the performance of this switchgear when interrupting a flowing three-phase loop current.

Generally, in a high-voltage substation, a double busbar is formed by two sets of busbars 1 and 2 running in parallel, as shown in the single-line diagram in Figure 1, and a busbar connection breaker 3, It is equipped with disconnectors 4, 5, 6, 7 and circuit breakers 8, 9. 10 is a transformer, and 11 is a power transmission line. Now, the transformer 10 transfers power from the power transmission line 11 to the disconnector 4, the bus 1, the disconnector 6, and the circuit breaker 9.
, and disconnectors 5 and 7 are assumed to be open. If this power is to be received via the bus bar 2 for reasons of operation of the substation, first the disconnector 5 is turned on, and then the disconnector 4 is opened. When this disconnector 5 is turned on, the current from the power transmission line 11 is divided into these two disconnectors, but the shunt current flowing through the disconnector 4 is commutated to the disconnector 5 when the disconnector 4 is opened. This commutation phenomenon is equivalent to forcing a current of the same magnitude and opposite direction as the shunt current of the disconnector 4 to flow along the loop 12. The voltage required for this forced flow is equal to the product of the impedance of the loop 12 and the shunt current flowing through the disconnector 4, and this voltage appears across the disconnector contacts as a recovery voltage after the disconnector 4 is opened. Next, the commutation phenomenon when the disconnector 7 is turned on and the disconnector 6 is opened is similar to that in which a current of the same magnitude as the shunt current of the disconnector 6 flows in the opposite direction along the loop 13. , and the voltage appearing across its disconnecting contacts after opening of the disconnector 6 is equal to the product of the impedance of the loop 13 and the shunt current of the disconnector 6. In addition, in the power transmission line, for example, as shown in Fig. 2, among the two parallel lines running between the bus 14 of the upper substation and the bus 15 of the lower substation, current flows from one line 16 through which current flows. When transferring a current to another line 17 that is not flowing, the current is once divided into two lines, and then a current of the same magnitude and opposite direction as the branched current of the first line is passed along the loop 18. By allowing it to flow, the result is the same as when the switching device 19 interrupts the loop current equal to the shunt current, and the power transmission line is switched.

The difference between breaking a loop current like this and breaking a normal short-circuit current is that the breaking current is small, ranging from several hundred to several thousand amperes, and the recovery voltage is low, ranging from several hundred to several thousand volts. During and after disconnection, the disconnection contacts of each phase have a potential equal to the phase voltage with respect to the ground on both the power supply side and the load side, and line voltage is applied between the disconnection parts of each phase. It is. The present invention relates to a device used in a method for testing the interruption of three-phase loop currents that are interrupted under such voltage conditions.

[Prior art and its problems]

FIG. 3 shows an example of a conventional interruption test method. In the figure, 21 is a three-phase power supply, each phase of which is a single-phase or three-phase transformer.
b, 22c secondary side low voltage windings 23a, 23b,
A predetermined breaking current and recovery voltage are supplied to the breaking parts 25a, 25b, 25c of each phase of the test switchgear 25 through the high voltage windings 24a, 23c.
4b, 24c to the cutoff section 2 of each phase of the switching equipment
A phase voltage corresponding to the rated voltage of the switchgear is supplied between 5a, 25b, 25c and a grounded metal container 25d that accommodates these interrupting parts.

According to this test method, the blocking portions 25a, 2 of each phase
During the continuation of the arc current in 5b and 25c,
In addition, even after the cutoff, phase voltage is applied between the cutoff part and the ground, and interphase voltage is applied between the cutoff parts, and the specified voltage is applied under exactly the same conditions as the actual circuit and in just one test. It has the advantage that it is possible to verify the breaking performance of the breaking section when interrupting a three-phase loop current, and to verify the insulation performance between the breaking section and the ground and between the breaking sections. On the other hand, in this test method, a phase voltage equivalent to the rated voltage of the switching equipment under test must be generated in the high voltage windings 24a, 24b, and 24c of the transformer even while the arc current continues, so the three-phase power supply 21 Each phase 21a, 2
It is necessary to minimize the voltage drop due to the internal impedance of 1b and 21c and the leakage impedance between the primary winding and the low voltage winding of the transformer. Among these impedances, the internal impedance of a three-phase power supply is already a small value because a large-capacity short-circuit generator is usually used as a three-phase power supply, so it is necessary to reduce the leakage impedance of the transformer. Yes, this means that a large capacity transformer is required. In addition, the voltage generated by the low-voltage winding on the secondary side of the transformer is a low voltage equivalent to the recovery voltage of the switchgear under test, but the ground insulation of this low-voltage winding shall be equivalent to the rated voltage of the switchgear under test. Moreover, it required three phases as well as a high voltage winding, which posed an economical problem as a test method.

FIG. 4 shows another example of a conventional interruption test method that takes economic efficiency into consideration. This test method uses a single-phase power supply 26, and in order to verify the current interrupting performance of the interrupter, first, a predetermined interrupting current and recovery voltage are supplied from the single-phase power supply to the interrupter 25a, for example, and the interrupting performance is verified. Next, in order to verify the insulation performance between the interrupting parts while the arc current is continuing and after the interruption, the metal container is insulated from the ground, and the arc energy generated in the metal container when the three-phase loop current is interrupted is verified. An equivalent single-phase current that produces the same arc energy as is supplied from the single-phase power supply 26 to the cut-off part 25a, and an electric current from another single-phase power supply 27 is supplied between the cut-off part 25a and the cut-off parts of the other phases that are connected together. It supplies phase-to-phase voltage. This test method involves heating by an arc in a sealed metal container.
Test results show that the insulation performance of thermally decomposed and ionized insulating gas is not uniquely related to the instantaneous value of the arc current at the interrupting part, but is determined by the total arc energy released into the metal container. The capacity of the single-phase power supply 26 is small because the terminal voltage is allowed to drop to almost zero while the arc current continues, and the capacity of the single-phase power supply 27 is based on the output. Since it does not require current, it has the advantage of requiring equipment of extremely small capacity, such as a test transformer, in terms of equipment costs. Moreover, when verifying the insulation performance between the interrupting parts and the ground instead of between the above-mentioned interrupting parts, the metal container 25d is grounded and the output voltage of the test transformer 27 is used as the phase voltage to connect the interrupting parts 25b and 25c. Verify ground insulation performance. For reference, when also verifying the ground insulation performance of the interrupting part 25a, use the grounded metal container 25d.
It is sufficient to insulate and support it again and connect it to the test power supply 27.

FIG. 5 shows an example of yet another conventional interruption test method that uses a single-phase power source similarly to FIG. 4. The biggest difference compared to the example in FIG. In order to protect the insulation of the single-phase power supply 28 from the above, a single-phase transformer 29 is interposed between this test cutoff section and the single-phase power supply 28. On the secondary side of this single-phase transformer, there is a low voltage winding 30a for supplying a predetermined breaking current and recovery voltage to the breaking section 25a.
and a high-voltage winding 30b for verifying the ground insulation performance of the interrupter 25a, and a reactor 31 for current adjustment is provided between the low-voltage winding 30a and the interrupter 25a.

To perform a test using the test circuit shown in Figure 5,
First, a predetermined cutoff current and recovery voltage are supplied to the cutoff section 25a from the low voltage winding 30a on the secondary side of the transformer via the reactor 31.
Verify the current interrupting performance of a. Of course, at this time, a phase voltage equivalent to the rated voltage of the test switchgear is generated in the high-voltage winding 30b, so when this breaking current is considered as an equivalent single-phase current as explained in the test method of Fig. 4, This means that the ground insulation performance equivalent to the original smaller breaking current has also been verified at the same time. To verify the ground insulation performance when a predetermined breaking current is passed through the three-phase breaking section, as described above, an equivalent single-phase current that produces the same arc energy as the three-phase arc energy is applied to the breaking section 25.
By flowing through a and blocking this, the blocking section 2
It is possible to verify the insulation performance between 5a and the earth, that is, the grounded metal container 25d. In addition, to verify the insulation performance between the interrupting parts, the metal container 2
5d is insulated and supported from the ground, and the high voltage winding 3
It is sufficient to use a tap such that the voltage generated at 0b becomes the phase-to-phase voltage. In this test method, the required voltage must be generated in the high-voltage winding 30b even while the arc current continues, so both the single-phase power supply 28 and the single-phase transformer 29 require relatively large capacities, but the number of Because only one piece is required, the economic burden on the equipment is smaller than that shown in Figure 3. However, the test methods shown in Figures 4 and 5 are both equivalent test methods using a single phase test, and the reliability of the test results obtained by these methods is not as good as that of the method shown in Figure 3 above. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device used in a three-phase loop current interruption test method that is highly reliable in test results and economical in terms of test equipment.

[Key points of the invention]

This invention is a test device for verifying the interrupting performance of a three-phase loop current for switchgear whose three-phase interrupting parts are housed in the same grounded metal container. The configuration is such that a predetermined breaking current and recovery voltage are supplied to each breaking section of each phase of the switchgear through the low voltage winding on the secondary side of each of the connected transformers, and the three-phase power supply A transformer having a primary winding separate from the transformer is provided in at least one of each phase of the transformer.
By supplying voltage for verifying insulation performance between the interrupting section of that phase and the ground or between the interrupting section of other phases through the high voltage winding installed on the next side, all phases of the interrupting section are In order to economically obtain test results under the same conditions as the actual circuit, the current interrupting performance of the interrupting section and the grounding or phase-to-phase insulation performance of the interrupting section are simultaneously verified when interrupting a predetermined loop current. It is something.

[Embodiments of the invention]

FIG. 6 shows an embodiment of a circuit configuration used in the three-phase loop current interruption test method according to the present invention. In the figure, 33 is a three-phase power supply, 33a, 33b, 33c
is a single-phase transformer having low-voltage windings 38a, 38b, and 38c connected to each phase thereof, and 37a, 37b, and 37c connected to each phase thereof, and supplying a predetermined breaking current and recovery voltage to the secondary side. These transformers may also be configured as three-phase transformers. 39 is transformer 37
A, 37b, and 37c are different transformers, and the voltage is used to verify the insulation performance between the cutoff part 25a of the test switchgear and the metal container 25d and between the cutoff parts 25b and 25c of other phases. A supply winding is provided on the secondary side, and a phase voltage is generated between tap B and the ground, and an interphase voltage is generated between the tap A and the ground. Further, 35 is an impedance representing a loop of an actual circuit, and is configured as a distributed constant circuit including a plurality of inductances and capacitances.

Low voltage winding 38 of transformers 37a, 37b, 37c
The terminal voltages of transformers 37a, 37a, 38b, and 38c are allowed to drop to a voltage sufficient to flow a predetermined arc current against the loop impedance 35 while the arc current continues.
The capacities of b and 37c can be extremely small. In addition, in such a small-capacity transformer, the leakage impedance between the primary winding and the secondary winding is large, so a large-capacity short-circuit generator with low internal impedance is usually used as the three-phase power supply 33. In addition to this, the voltage at the inlet of the primary winding is maintained at approximately the same value as when no load is applied to the three-phase power supply. can generate an insulation verification voltage of Note that this transformer 39 does not require an output current, so it may have an extremely small capacity.

A three-phase loop current interruption test using this circuit configuration is performed as follows. That is, transformer 39
The tap B of the high-voltage winding 40 is connected to the connection terminal C of the low-voltage winding 38a to maintain the ground potential of the cut-off part 25a at the phase voltage, and the metal container 25d is grounded to connect the three-phase cut-off parts 25a, 25b, 25c. interrupts the three-phase loop current. At this time, the voltage applied between the interrupting part 25a and the grounded metal container 25d is maintained at the phase voltage value while the arc current continues and after the interruption, and the ground insulation performance of the interrupting part 25a is maintained under the same conditions as the actual circuit. is verified simultaneously with the current interrupting performance of each phase interrupter. Next, tap B of the high-voltage winding 40 of the transformer 39 is switched to tap A to make the output voltage of the high-voltage winding the phase-to-phase voltage, and after supporting the metal container 25d insulated from the ground, the three-phase interrupting section 25a,
25b and 25c interrupt the three-phase loop current. At this time, the blocking section 25a and the blocking section 25 of the other phase
b, 25c is maintained at the phase-to-phase voltage during the continuation of the arc current and even after the interruption, and the voltage applied between the interruption portion 25a and the interruption portion 25 of the other phase is maintained under the same conditions as in the actual circuit.
b, 25c is verified at the same time as the current interrupting performance of each phase interrupting section.

In the above embodiment, the transformer 39 having a high voltage winding is connected only to one phase (here, phase A) of a three-phase power supply, but as shown in FIG. If a transformer with a high voltage winding is placed not only in the a phase but also in other phases such as 39b and 39c, and the metal container 25d is grounded,
Because the capacity of the transformers 39b and 39c is small, it is possible to verify the current interrupting performance of each phase interrupting section when interrupting a predetermined three-phase loop current, and to connect the interrupting section to the earth without any significant increase in the economic burden as test equipment. Verification of insulation performance between and between phases is possible with a single test.

〔Effect of the invention〕

This invention is a test device for verifying the interrupting performance of a three-phase loop current for switchgear whose three-phase interrupting parts are housed in the same grounded metal container. The configuration is such that a predetermined breaking current and recovery voltage are supplied to each breaking section of each phase of the switchgear through the low voltage winding on the secondary side of each of the connected transformers, and the three-phase power supply A transformer having a primary winding separate from the transformer is provided in at least one of each phase of the transformer.
A voltage for verifying insulation performance is supplied between the interrupting section of that phase and the ground or between the interrupting section of the other phase via the high-voltage winding installed on the next side, so that it can be compared with the actual circuit. Tests can be performed under the same conditions, highly reliable test results can be obtained, and the test equipment can have a small capacity, reducing the economic burden.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the order of operation of disconnectors and the route of loop current when switching the busbar of a substation. Figure 2 is the order of operation of switchgear and the route of loop current when switching the power transmission line. Figure 3 is an example of a conventional three-phase loop current interruption test circuit using a three-phase power supply, and Figure 4 is an example of a three-phase loop current interruption test using a single-phase test. The first example of a conventional test circuit is shown in FIG. 5, and the second example of a conventional test circuit is shown in FIG. A first embodiment of a three-phase loop current interrupting test circuit, and FIG. 7 similarly shows a second embodiment. 21, 33...Three-phase power supply, 21a, 21b, 2
1c, 33a, 33b, 33c...Each phase of three-phase power supply, 25...Switching equipment, 25a, 25b, 25c
...Shutoff part for each phase of switching equipment, 25d... Grounding metal container of switching equipment, 37a, 37b, 37c...
a transformer that provides a predetermined breaking current and recovery voltage;
39, 39a, 39b, 39c...another transformer,
40, 40a, 40b, 40c...high voltage winding.

Claims (1)

[Claims] 1 A test device for verifying the interrupting performance of three-phase loop current for switchgear in which the three-phase interrupting parts are housed in the same grounded metal container, and the primary winding is connected to each phase of the three-phase power supply. 2 of each of the transformers
The configuration is such that a predetermined cutoff current and recovery voltage are supplied to each cutoff section of each phase of the switching equipment via a low voltage winding on the next side, and the cutoff current and recovery voltage are supplied to at least one of each phase of the three-phase power supply. A transformer with a primary winding separate from the transformer is provided, and the connection between the interrupting part of that phase and the earth or with the interrupting part of other phases is provided through the high voltage winding provided on the secondary side of the transformer. A three-phase loop current interrupting test device characterized by having a configuration in which a voltage for verifying insulation performance is supplied between the three-phase loop currents.